module Eliom_cscache : sig..end
Client-server cache for Eliom applications, that is used both for keeping data on client side or keeping values in memory during a request.
When you get a piece of data through Eliom_cscache from client-side, the request to the server is done only if the data is not already in the client-side cache.
On server side, Eliom_cscache is using a temporary cache (with "request" scope) to avoid fetching the data several time from the database during the same request. This server-side cache is automatically sent to the client to fill the client-side cache. If you want to avoid too many requests from the client, prefill the server-side cache with the data the client program will need.
This module hides many subtelties that are useful for client-server (possibly reactive) applications, like, for example, handling delays correctly both on client and server sides.
In the near future, Eliom_cscache will make it possible to save persistent data, which is useful for implementing off-line applications.
type ('a, 'b) t
The type of association tables (implemented using Hashtbl)
val find : ('a, 'b) t -> ('a -> 'b Lwt.t) -> 'a -> 'b Lwt.t
find cache get_from_db key returns the value associated to key in cache. If not present, it calls get_from_db to fetch the data from the database. get_from_db must be implemented both server and client sides. Several simultaneous call to find will result in a single call to get_from_db. Exceptions are not cached.
val do_cache : ('a, 'b) t -> 'a -> 'b -> unit
do_cache cache key value adds the association from key to value in cache, or replaces it if not already present. Called from client side, it affects only client side cache. Called from server side, it will have effect both on the server cache (scope: request) and the client side cache.
val local_find : ('a, 'b) t -> 'a -> 'b Lwt.t
Find a piece of data in local cache, without trying to fetch it from server. Raises Not_found instead. If the value is currently being retrieved, it waits for it to be ready before returning.
val find_if_ready : ('a, 'b) t -> 'a -> 'b
Find a piece of data in local cache, without trying to fetch it from server. Raises Not_found instead. If the value is currently being retrieved, it raises Not_ready.
Load (or reload) in cache the piece of data from server
val create : unit -> ('a, 'b) t
Create a new table. Must be called from server side.